Trigger anti-backlash device for firearms



Nov. 22, 1960 ca. WILHELM TRIGGER ANTI-BACKLASH DEVICE FOR FIREARMS Filed Feb. 6, 1959 O 4 3 3 I 6 @W E: 0. 1 a, i z 2 mm /6 a ll 2 I. I0 I 4 INVENTOR GAR Y WIL HELM 61's ATTORNEYS.

tates aent 2,960,788 Patented Nov. 22, 1960 ice.

TRIGGER ANTI-BACKLASH DEVICE FOR FIREARMS Gary Wilhelm, New Haven, Conn., assignor to The High Standard Manufacturing Corporation, Hamden, Conn., a corporation of Connecticut Filed Feb. 6, 1959, Ser. No. 791,598

4 Claims. (Cl. 42-69) This invention relates to trigger adjustments for firearms, and it relates more particularly to trigger antibacklash devices therefor.

Trigger backlash, so-called, is caused by an excessive amount of movement or travel of the trigger beyond the point in the over-all travel of the trigger where the firing member, such as the hammer or cocking device, is released in order to fire the cartridge. During this movement, there is so little resistance to the finger pull on the trigger as compared to that before the firing member is released that it is as if the trigger were suddenly relieved of any resistance at all. Triggers with a large amount of such over-travel, so to speak, and resulting backlash are undesirable because the trigger finger picks up a great deal of momentum if it is permitted to move. even a small distance after the firing member is released. Backlash therefore makes the gun move off the target just at the instant that it is fired. It is accordingly desirable to reduce the amount of backlash in the trigger as muchas possible without interfering with proper release of the firing member.

Anti-backlash devices, which have been provided heretofore for this purpose, usually consist of a screw mounted in the frame of the gun with one end extending into the path of the trigger so as to limit its free rearward travel. The screw is disposed with its longitudinal axis extending in the direction of travel of the trigger so that the end of the screw provides a. stop for the trigger. By adjusting the screw in or out, it is moved endwise toward or away from the trigger, thereby varying the distance that the trigger is permitted to move. A binding screw or spring detent may be provided in order to prevent accidental rotation of the adjusting screw once it has been set at the desired position. A disadvantage of such. prior anti-backlash device is that it is difiicult to provide a suitable detent mechanism which is adaptable to large-scale production. Furthermore, it is not always possible, due to the location and arrangement of the trigger mechanism, to mount the anti-backlash screw Where it can engage the trigger, and still be accessible for adjustment without dismantling the gun. In addition, fine adjustment of the anti-backlash screw is not always feasible due to the fact that even a screw with a fine thread may not provide close enough adjustment when a detent is employed in combination therewith.

It is accordingly an object of the present invention to provide an improved anti-backlash device which is free of the disadvantages of prior devices of this kind, and which is inexpensive to manufacture and readily adjustable without disassembling the gun. A further object of the invention is to provide an anti-backlash device having finer adjustment than is ordinarily feasible, while still another object is to provide a more positive and rugged, yet less expensive, detent means for an anti-backlash screw.

With the above objects in. view and some others which will be apparent to those skilled in the artfrom the description hereinafter, an anti-backlash device embodying the invention comprises a screw mounted in the frame of a gun with its longitudinal axis disposed transversely to the direction of travel of the trigger and in position so that it will be engaged laterally by the trigger when the latter is retracted, thereby positively limiting the rearward travel of the trigger. The screw is provided with a conical surface along its length against which the trigger is stopped, such conical surface being co-axial with the longitudinal axis of the screw so that as the screw is rotated and moves longitudinally the stop-surface contacted by the trigger moves away from or closer to the trigger, thereby increasing or decreasing the amount by which the trigger may be rotated.

In accordance with a further aspect of the present invention, spring-detent means are provided, which engage laterally facing detent-surfaces on a portion of the antibacklash screw, such that said screw may be rotated in predetermined steps in order to facilitate adjustment of the screw and at the same time to prevent accidental rotation of said screw once it has been properly adjusted. In this connection, provision of the above-mentioned conical surface on the anti-backlash screw makes possible a much finer adjustment for eliminating backlash than has been practical heretofore where detent means have been employed. Thus, since provision of the detent or so-called click-action in the anti-backlash screw neces sarily precludes settings between the steps defined by the detent, it is important that with each rotational stepof the adjusting screw the amount of adjustment thus made in the travel of the trigger be extremely small. It is, moreover, desirable in order to obtain a comparatively strong detent action, to rotate the adjusting screw on the order of a quarter or a half a turn between clicks. It will be appreciated therefore that by providing the conical surface on the anti-backlash screw, the amount of adjustment in trigger-travel for each quarter turn, for example, of such screw may be substantially reduced as compared with that caused by a quarter turn of the backlash screw of prior devices.

Other advantages and novel features of the invention. will become apparent from the following detailed description of one particularly desirable embodiment of the invention, which is illustrated in the accompanying drawings, wherein Fig. 1 is a side elevational view, partly broken away and partly in cross-section, of a pistol incorporating the invention;

Fig. 2 is a vertical cross-section on an enlarged scale and taken on the line 22 of Fig. 1;

Fig. 3 is a perspective view of the trigger anti-backlash screw; and

Fig. 4 is a horizontal section of a taken on the line 44 of Fig. 2.

With reference to the drawings, the pistol there shown includes a slide 10 mounted for longitudinal reciprocation on a frame 12 into and out of battery position in which the forward face of slide 10 is in intimate abutting engagement with the rear face of the barrel 14, as shown in Fig. 1. A trigger 16, having a finger piece 18 and an upwardly extending post 20, is pivoted intermediate its ends on a pin 22, mounted in the frame 12 transversely thereof. Pivoted to the upper end of the post 20 by means of a pivot pin 23 is a sear bar 24 extending rearwardly and releasably engaged withthe sear 26 in order to pivot the latter counterclockwise, as shown in Fig. 1, upon retraction of trigger 16, thereby releasing the cocked hammer 28 which is violently swung by the hammer spring 30 into its broken line position against a firing pin 32 mounted in slide 10. A sear spring 34 urges the depending sear nose 36 of scar 26 into cocking engagement with the sear notch 38 on the hammer when the latter is pivoted back upon retraction of slide 10.

portion of the piston.

Forwardly of trigger 16, the pistol is provided with a barrel takedown device indicated generally by the reference numeral 40. Takedown device 40 comprises a locking pin or stud 42 rigidly secured in the underside of barrel 14 and extending downwardly through a vertical passage in frame 12 into interlocking relation with an actuating plunger 44 mounted for longitudinal movement in a passage 46 extending transversely of pin 42. Plunger 44 is disposed generally longitudinally of the frame 12 of the pistol and projects outwardly beyond the front edge of the frame just above the trigger guard. Longitudinal movement of actuating plunger 44 outwardly or forwardly of frame 12 causes wedge-surfaces 48 on the underside of plunger 44 to engage locking stud 42 and draw it downwardly, firmly locking barrel 14 on the mounting bed of frame 12 in the manner disclosed in an application of Harry H. Sefried II, Ser. No. 787,- 490, filed January 19, 1959. A coil spring 50 located at the inner end of passage 46 urges actuating plunger 44 outwardly into locking relation with the locking stud 42.

Located forwardly of trigger post 20 is an adjusting screw 52 disposed transversely thereof in a space 54 provided therefor in frame 12 by a hole drilled from the closed end 56 of passage 46 into the space occupied by the upper end of trigger 16. Adjusting screw 52, herein sometimes referred to as the anti-backlash screw or trigger backlash adjusting screw, is best shown in Figs. 2, 3 and 4 of the drawings, and is provided at one end with a cylindrical head-portion 58 fitting within a transverse cylindrical passage 60 in frame 12. A slot 62 is formed in the outer surface of head-portion 58 to receive a screw driver or similar tool for rotating screw 52. The opposite end of screw 52 is, in this instance, substantially smaller in diameter than the head-portion 58 and comprises a threaded section 64 which is threadedly received in a tapped hole 66 in frame 12 on the opposite side of space 54 from transverse passage 60.

Inwardly of threaded section 64 is formed a conical portion 68, the axis of which coincides with the longitudinal axis of screw 52. As best seen in Fig. 4, trigger post 20 will engage conical surface 68 of adjusting screw 52 when trigger 16 is fully retracted. Consequently, by rotating screw 52 so that it moves in the direction of its longitudinal axis, the point at which the rearward movement of the finger piece 18 of the trigger is stopped will be shifted either forward or back depending on which direction the adjusting screw 52 is turned. If it is turned so that it moves to the right as viewed in Fig. 4, the trigger post 20 will engage adjusting screw 52 on a wider part of the conical surface 68, and the travel of the trigger will be reduced. On the other hand, if the adjusting or anti-backlash screw 52 is turned so that it moves to the left in the drawings, post 20 engages conical surface 68 nearer the vertex of the cone, and the trigger fingerpiece 18 is therefore allowed to move further in its rearward travel. It will be appreciated of course that the variations in the amount of trigger travel are very small, particularly where the total trigger-travel is small, as is most desirable.

It should be noted here that so long as the vertex angle of the cone of conical surface 68 is less than 90, the amount of trigger-travel adjustment will be less than the amount of longitudinal movement of adjusting screw 52 required to produce that much change in triggertravel. For example, if the vertex angle of the cone of surface 68 is 45, which has been found to be desirable, adjusting screw 52 will move longitudinally twice as far as the amount of adjustment in trigger-travel effected by such longitudinal movement of screw 52. Consequently, standard threads can be used for screw 52, and adjustment can be made in fairly large increments of rotation of the screw, while at the same time providing very fine adjustment of the trigger for backlash. The importance of this will be more apparent from the description hereinafter of the detent means provided for adjusting screw 52. In adjusting the trigger in order to eliminate backlash, the ultimate object is to reduce the amount of travel of the trigger beyond the release point to as near zero as is possible. If this could be accomplished the movement of the trigger would be arrested exactly at the instant that the hammer is released and there would be no backlash at all. From a practical standpoint this can not be completely accomplished, but it will be appreciated that the finer the adjustment for backlash, the closer this ultimate setting can be reached.

Adjusting screw 52 is provided in this instance with a square shank 70 adjacent head-portion 58 and intersecting the conical surface 68. There are therefore four fiat surfaces 72 formed thereon at right angles to each other and providing laterally facing detent surfaces, which are engageable by a spring-detent to be described. As will be seen in Figs. 1 and 4, adjusting screw 52 projects laterally into the end of passage 46 for the takedown device 40 and into engagement with a washer 74 located at the rear end of the takedown actuator spring 50. Washer 74 is held slightly out of contact with the end wall 56 of passage 46 by the lateral faces 72 of adjusting screw 52 with the result that spring 50 continu ously presses washer 74 rearwardly against the detent surfaces of screw 52. It will be apparent that in order to rotate adjusting screw 52, spring 50 must be compressed as each corner of the square shank 70 presses against washer 74, until it passes to the other side. Spring 50 will then snap washer 74 into full engagement with the next detent surface 72, thereby providing a strong click-adjustment for the anti-backlash screw 52.

It is of course feasible to provide other polygonal shapes for the detent portion 70 of screw 52, such as a hexagonal shank, but the greater the number of sides, the less effective is the detent-action. On the other hand, if it is necessary to obtaIn finer adjustment in order to elfminate trigger backlash, it might be found more desirable to sacrifice the more rugged detent-action of the square shank in order to reduce the amount of rotation of screw 52 in each step. It is of course also possible to form recesses in the periphery of the shank of screw 52 and to provide a spring-loaded plunger in place of the flat washer 74.

However, an advantage of the specific arrangement shown in the drawings is that the clicks are unmistakably sharp and audible. Furthermore, since finer adjustment is made in the so-called backlash travel by the conical surface of the adjusting screw, it is possible to make the rotation of the screw in larger, and therefore more apparent, quarter turns. If desired, half or even full turns of the adjusting screw between clicks could be provided by decreasing the angle of the conical surface 68 on screw 52. On the other hand, in order to provide still finer adjustment, it might be found desirable to decrease the angle of the conical surface 68 on screw 5'2 regardless of the size of steps provided by the detent device.

What is claimed is:

1. An anti-backlash device for a trigger supported on the frame of a firearm comprising an adjusting screw mounted in said frame with its longitudinal axis disposed transversely of the direction of travel of said trigger in position for lateral engagement thereby when said trigger is retracted, in order to positively limit the rearward travel of said trigger, said screw having a conical surface formed in the area contacted by said trigger, said conical surface being co-axial with the longitudinal axis of said screw such that axial adjustment thereof adjusts the limit of movement of said trigger when it is retracted.

2. An anti-backlash device as defined in claim 1, wherein a portion of said screw is provided with laterally facing detent-surfaces on its periphery and spring-detent means mounted in said frame adjacent the detent-surfaces of said screw, said detent means being engageable with said detent-surfaces in order to inhibit rotation of said screw.

3. An anti-backlash device as defined in claim 2, wherein said screw is provided adjacent one end with a cylindrical head-portion rotatably received in a cylindrical aperture in said frame, said detent-surfaces comprising a polygonally-shaped section of the shank of said screw adjacent to and inwardly of said head-portion with said conical surface intersecting said polygonally-shaped section, said screw being thrcadedly received at its end opposite from said head-portion in a threaded aperture in said frame.

4. An anti-backlash device as defined in claim 5, wherein said spring-detent means comprises a coil spring having its axis disposed transversely to the longitudinal axis of said screw, said spring being under compression and exerting pressure in one direction against said detent-surface of said screw and in the other direction against an actuating member for a barrel takedown device for the firearm.

References Cited in the file of this patent UNITED STATES PATENTS 1,062,418 Rojohn et al. May 20, 1913 2,126,076 Wright et al. Aug. 9, 1938 

